Evaluation of Geometric Effect on the Pseudo-Static Seismic Coefficient in Embankment Dams

Abstract

Selection of appropriate seismic coefficients considering the geometry, stiffness and damping of materials is the foremost part of analysis in Pseudo-static approach. So Masjed Soleiman dam for a case study has been selected. Finite Element model of Masjed Soleiman dam has been constructed in GeoStudio-Geoslope software. Also in constructing of finite element model, has been used of Mohr-Coulomb failure criterion for body of dam. For analyses of finite element model, first a layer analysis has been carried out considering 12 layers in end of construction stage. Then, this analysis has been continued considering water table and weight of dam reservoir. 2 earthquake records in the far field condition have been applied horizontally to the bedrock as the input for dynamic analysis. In this study, to perform stability analysis and calculate the factor of safety, critical sliding surface on downstream that was reported by the consultant engineers have been considered. The semi empirical Newmark method for estimating permanent earthquake-related deformation of slopes is based on the sliding block framework. This conceptual framework approximates the potential sliding mass as a rigid body resting on a rigid sloping base. Assuming the allowable permanent deformations to be 300mm, a new perspective on dynamic factor of safety is proposed in this research. Also, in order to investigate the variations of pseudo-static acceleration coefficient along the height of dam, all analyses have been carried out in static, pseudo-static and dynamic conditions for the Masjed Soleiman dam assuming various geometrical properties. The results demonstrate a decrease in acceleration with increase in the height of dam and also an increase in the acceleration with steepening the slopes.

Keywords: Embankment dams, Pseudo-static method, Dynamic analysis, Masjed Soleiman dam

Keywords

• Embankment dams, Pseudo-static method, Dynamic analysis, Masjed Soleiman dam

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